1. Field of the Invention
The present invention relates generally to a method of forming a polygon image, and more particularly, to a method of forming an animation image in real time by the polygon image, as well as to an image processing apparatus using the same.
2. Description of the Related Art
In recent years, in order to give the virtual sense for the real by use of a computer graphic (CG) technique with respect to an image processing apparatus by use of a computer such as a gate unit or the like, a development is made for forming an image model (hereinafter merely called a model) which is called a character, an object, or a model of details nearer to the actual, by use of a polygon which has a plurality of polygonal faces.
For this reason, it is general that a texture having each tone is pasted up in a plurality of polygons constituting a model.
That is, in a hardware in a game unit under the present condition, color data are given as apex data to respective apexes of the polygon forming the model. A color of each pixel in the polygon is plotted by the hardware, while the color at the apex is interpolated. Thus, the texture in each polygon can be plotted having a smooth tone. Furthermore, a polygon edge is not marked in a generic model by this method.
On the other hand, it is possible to constitute a reflection by an animation image. A plurality of cell images are continuously projected in the prior art, so that it is public domain that the animation image having a motion can be obtained.
It is desirable in recent years that such the animation image is displayed even in the image processing apparatus using a computer such as a game unit or the like.
For this reason, there is a technique which is called a toon rendering in which a special rendering process is executed by a dedicated three-dimensional process software, thereby simplifying a tone of the texture of the polygon constituting the model, to form a picture similar to an animation picture.
On the other hand, it is difficult to obtain the picture similar to the animation picture by the hardware in the game unit under the present condition without using such the special technique.
That is, as a plotting process is performed by the hardware, while a color of each apex is interpolated, the texture of the polygon is plotted having the tone. Thus, in the polygon to be plotted, the cubic sense is excessively emphasized and the atmosphere as the animation picture is impaired.